Coatings are often used to protect surfaces against wear and corrosion. The coatings are generally composed of binders, fillers, and other ingredients. The binders, upon curing, bind the fillers and other ingredients to each other and to the substrate. The fillers are added principally as reinforcing agents; to increase corrosion resistance; to increase abrasion resistance; to increase surface lubricity; and/or to increase the load of total solids (which increases the coating's dried-to-wet ratio and, therefore, reduces the drying shrinkage and the resultant stress cracks). Other ingredients are added to modify physical properties of the surface, such as its color (e.g., the pigment in a paint).
Coatings bond to a surface by means of coupling agents. Coupling agents form bonds between the binder in the coating and the surface to be coated. They can also contribute to the cohesive strength of coatings comprising polymer chains by cross-linking the polymer chains. The use of organosilanes as coupling agents is discussed in an article by Barry Arkles entitled "Silane Coupling Agent Chemistry," which was published in "Silicone Compounds Register and Review (S-7)," by R. Anderson, B. Arkles, and G. L. Larson (Petrach Systems, 1987), and in an article by Warde T. Collins entitled "Adhesion Promoters," which was published as Chapter 10 in "Handbook of Coatings Additives," edited by Leonard Kelbo (Marcel Dekker, 1987). The latter article is distributed by Dow Corning as Brochure No. 24-481-87.
Silica-based coatings known in the art have silica to alkaline-metal-oxide molar ratios in the binder no higher than 6.5:1. These coatings require the application of heat to bind to the surfaces of the material being coated. Moreover, these coatings do not form true amorphous ceramic matrices at room temperature.